In the current laser projection system, a laser light source is used to emit a laser beam to excite a phosphor agent in order to generate color lights with different wavelengths. Since the laser beam has high energy and high collimation, the temperature of the laser beam is extremely high (e.g. the temperature may be close to or higher than 1000° C.), and the phosphor agent is readily burnt out. Nowadays, the phosphor agent is coated on an outer-ring portion of a phosphor wheel (also referred as color wheel), and the phosphor wheel is driven by a motor to be rotated at a high speed. Consequently, the energy absorbed by the phosphor agent per unit time is reduced, and the heat-dissipating efficacy is achieved. However, with the increasing demands on the luminance of optical products, the required energy of the laser light sources are gradually increased. For meeting the luminance requirements, the area of the phosphor wheel is gradually increased. Under this circumstance, the optical path of illuminating the phosphor agent is increased, and the energy absorbed by the phosphor agent per unit time is increased.
However, the increased area of the phosphor wheel may bring some problems. For example, since the size of the phosphor wheel is increased, the system space of the laser projection system is correspondingly increased. In other words, the overall volume of the laser projection system is increased. Moreover, after the size of the phosphor wheel is increased, the high speed motor should be upgraded to maintain its high speed. Since the area of the phosphor wheel is increased, it is difficult to maintain the balance of the phosphor wheel. As known, there are few commercially-available motors that match the large-sized phosphor wheel. Even if the motor matching the large-sized phosphor wheel is acquired, associated accessories of the motor should be developed. Moreover, as the speed of the motor is increased, the problem of causing noise is increased. Due to the limitations of the size of the phosphor wheel and the corresponding requirement of the motor, the high energy laser light source is not suitably used in the conventional laser projection system. In other words, if the area of the phosphor wheel and the rotating speed of the motor fail to be increased, the luminance of the laser projection system is restricted.
Moreover, even if the rotating speed of the motor for rotating the phosphor wheel is increased, since the phosphor wheel has a circular disc profile, another problem occurs. For example, it is difficult to cause a pressure difference of the ambient air during rotation of the phosphor wheel. Since the airflow cannot be effectively driven, the heat-dissipating efficacy is usually unsatisfied.
Therefore, there is a need of providing a phosphor wheel heat-dissipating module for effectively removing heat from a phosphor wheel of a laser projection system without increasing the area of the phosphor wheel.